Poser2D is a easy tool for Unity to create a 2d skinned mesh model with animations.
Easy rebuild polygons of  mesh.
Easy create a skeleton.
Easy bind bones to meshs.
Easy modify bone weights of vertices.
Easy control pose of model.
Easy record poses and reload them for making animations.
Easy convert sprites to meshs and merge meshs to one

It exports pure models and animaitons without any edit data.
Performance issues just need to look at

How to use it in Unity?
Import all Poser2D scripts then opening the Poser2d Window to create a new 2d character.